Apparatus for adsorbing carbon dioxide from air in a storage system

ABSTRACT

The system for circulating the air from the storage room and for regenerating the active solid adsorbent in the adsorption chamber includes a reversible blower and a series of check valves. The check valves alternately close off the adsorption chamber either from the storage room or from a source of desorbent while opening the chamber to the source of desorbent or the storage room, respectively. The check valves are controlled by the pressure of the air in the storage room and the pressure of the desorbent.

United States Patent [191 Schmid June 26, 1973 APPARATUS FOR ADSORBINGCARBON DIOXIDE FROM AIR IN A STORAGE SYSTEM [75] Inventor: EmmerichSchmid, Winterthur,

Switzerland [73] Assignee: Sulzer Brothers Ltd., Winterthur,

Switzerland 22 Filed: Apr. 20, 1972 211 Appl. No.: 245,817

[30] Foreign Application Priority Data May 25, 1971 Switzerland 7597/71[52] US. Cl 551/179, 55/68, 55/196, 55/387, 99/476, 99/646 [51] Int. Cl.Q B0ld 53/04 [58] Field of Search 55/25, 26, 68, 74, 55/179, 196, 387;99/476, 646

[56] References Cited UNITED STATES PATENTS 3,186,150 6/1965 Zankey55/387 3,203,771 8/1965 Brown et a]. 55/68 X 3,313,631 4/1967 Jensen99/475 3,323,288 6/1967 Cheung et a1.... 55/179 X 3,594,986 7/1971Schmid 55/68 3,621,585 11/1971 Robertson 55/179 X Primary Examiner-SamihN. Zaharna Assistant ExaminerRichard W. Burks Attorney-Francis C. Hand,Hugh A. Chapin et al.

[57] ABSTRACT The system for circulating the air from the storage roomand for regenerating the active solid adsorbent in the adsorptionchamber includes a reversible blower and a series of check valves. Thecheck valves alternately close off the adsorption chamber either fromthe storage room or from a source of desorbent while opening the chamberto the source of desorbent or the storage room, respectively. The checkvalves are controlled by the pressure of the air in the storage room andthe pressure of the desorbent.

3 Claims, 2 Drawing Figures APPARATUS FOR ADSORBING CARBON DIOXIDE FROMAIR IN A STORAGE SYSTEM This invention relates to an apparatus foradsobring carbon dioxide from air in a storage system, particularly, astorage system for fruit, vegatables, flowers, mushrooms and the like.

Heretofore, it has been known to store various perishable or oxidizableproducts, such as fruit, in a refrigerated condition in order topreserve the value of the products until delivery. Also, it has beenknown to obtain a further ripening of products such as green fruit instorage by heating. Further, in some instances, it has been known forunripe fruit or the like to be stored initially for a period of time ina refrigerated premise, and then to be given a further ripening byheating in the same premise shortly before delivery to users.

In all cases, the carbon dioxide content of the air present in thestorage premises must be reduced to a particular percentage, and forfurther ripening processes, the carbon dioxide content must beconsiderably reduced still further. For instance, fruits or the like canbe given simple storage satisfactorily for several months inrefrigerated storage chambers if the atmosphere is supervised andadjusted appropriately and if the carbon dioxide (CO content of the airin the storage premises is satisfactory.

As is known, the vital functions of fruit, such as apples or the like,continue after cropping, such that oxygen is constantly consumed whilecarbon dioxide (CO is evolved. The fruit ages faster in proportion asthese respiratory events with their consumption or sugar and othernutrients, proceed. Thus, it has become practicable to slow down therespiration or breathing rate of such products in order to increasestorage life. One way of slowing down the respiration rate has been toconsiderably reduce the oxygen content of the atmosphere in the storagepremises as compared with the oxygen content of ordinary air. Forexample, for the storage of fruit, the reduction is conveniently tosomething like 3 percent of the normal oxygen content.

One known process for providing an atmosphere differing from thecomposition of normal air in this way as regards oxygen and carbondioxide (CO content, in the case of fruit stored in refrigerated andexternally gas-tight storage premises, has been to remove down to arequired percentage the carbon dioxide which the stored fruit yields tothe atmosphere in the premises in exchange for the oxygen which is takenup. That is, during respiration, the stored fruit or the like consumesmore and more of the oxygen present in the air in the premises whileproducing more and more carbon dioxide. Once the desired minimum ofabout 3 percent oxygen content has been reached, this level can bemaintained subsequently by a supply of atmospheric air. Even better, theoxygen content ofthe air in the storage premises can be artificiallyreduced to the required value.

Active carbon and zeolite have been known to make good solid adsorbents.However, the term solid adsorbents" as used for the purposes of thisinvention is to be understood as covering cases in which a granularsolid, such as gravel, forms the support for a liquid adsorbent, such asa potash solution.

Further, in adsorption apparatus for reducing solid regenerableadsorbents, it has been known to regenerate the solid adsorbent, oncethe adsorbent has become saturated e.g., active carbon saturated bycarbon dioxide, by means of a desorption gas, preferably freshatmospheric air.

Conventionally, in order to change over from premises air to fresh airand vice versa, use has been made of various change-over valves whichare disposed in the supply and removal lines and which are operated byelectric or hydraulic or pneumatic drives. Further, extra drive systemshave been required to operate the change-over valves. As a result,reliable operation of an adsorption apparatus has been largely dependentupon the operating reliability and seal-tightness of the valves whichalso require fairly large torques for their operation. The known systemshave therefore been unsatisfactory in construction and consume excessivepower.

Accordingly, it is an object of this invention to pro vide an adsorptionapparatus which is economic to operate and which uses simple change-overelements.

It is another object of the invention to effect a rapid change-over inthe air supplied to a storage room for perishable products.

It is another object of the invention to eliminate the need forauxiliary drives and transmissions for changing over a valve from onestate to another in an adsorption apparatus.

Briefly, the invention is directed to an adsorption apparatus for astorage room with an adsorption chamber, a pair of lines for conveyingpremises air from the storage room through the adsorption chamber andback to the storage room, a pair of lines for conveying a desorbentthrough the adsorption chamber, and a pair of lines, each of which isconnected in common to each of one line for desorbent and one line forpremises air and to the adsorption chamber. The invention provides thisapparatus with a reversible blower in one of the common lines and aplurality of check valves in the respective lines for the premises airand the desorbent. The check valves are controlled by the pressure ofthe air in the storage room and by the pressure of the desorbent,respectively. That is, when the premises air is being circulated throughthe adsorption chamber during an adsorption period, the pressure of theair opens the check valves for the lines to the storage room while thecheck valves in the lines for the desorbent remain closed. At this time,the blower is operated to circulate the premises air through theadsorption chamber. Upon reversal of the blower for a regenerationperiod, the check valves for the lines to the storage room close and thecheck valves in the lines for the desorbent open.

In another embodiment, the adsorption apparatus has a pair of adsorptionchambers which are operated in alternation so that while one undergoesan adsorp tion cycle, the other undergoes a regeneration cycle. In

this case, a reversible blower is connected to each adsorption chamberwithin a line common to a premise air line and a desorbent line. Also,each premise air line and each desorbent line is in parallel with a mainline to the respective storage room or desorbent supply.

The invention makes it possible to use automatic commercially availablecheck valves made e.g. of a plastic such as polyvinyl chloride (PVC).Upon completion of an adsorption or regeneration period, the blower canbe reversed, e.g. by changing over phases of the electricity supply toits motor.

These and other objects and advantages of the invention will become moreapparent from the following detailed description and appended claimstaken in conjunction with the accompanying drawings in which:

FIG. 1 schematically illustrates an apparatus having one adsorptionchamber according to the invention; and

FIG. 2 schematically illustrates an apparatus having two adsorptionchambers according to the invention in which at any time, and inalternate relationship, adsorption proceeds in one chamber andregeneration of the adsorbent in the other.

Referring to FIG. 1, an adsorption chamber 1 contains a charge of solidadsorbent such as active carbon grains. A line 2 is connected to thebottom of chamber 1 in which a reversible blower 3 is mounted in ordereither to circulate air from a storage room or premises 4 through theadsorption chamber 1 via an outlet line 5 and back to the premises 4 viaa return line 7 or to convey fresh air as a desorbent through theadsorption chamber 1 via an input line 9 and an outlet line 10. Theoutlet line 5 from the storage premises 4 and the outlet line 10 for thedesorbent are connected in common to the line 2 through the blower 3.Similarly, the return line 7 and the desorbent input line 9 areconnected in common to each other through a line 13 on the opposite sideof adsorption chamber 1 from the blower 3. In addition, a check valve 6is positioned in the outlet line 5 and like check valves 8, ll, 12 arepositioned in the respective lines 7, 9, 10.

During an adsorption period or phase, check valve 6 is open andblower 3,which can be a reciprocating compressor or a rotary compressor, isoperative counter-clockwise and conveys air from premises 4 through line5 and through chamber 1 with adsorption of carbon dioxide (C0,). The airreturns to premises 4 from chamber 1 through line 7 and open check valve8. During this adsorption phase, check valves 11, 12 in lines 9, 10,respectively, are closed.

During a regeneration phase, the blower 3 is reversed, for example bymeans of a timer or manually, to operate clockwise and check valves l1,12 are open to convey fresh air through the adsorption chamber 1 toregenerate the active carbon grains by removing the carbon dioxide as isknown. At this time, the check valves 6, 8 in the lines 5, 7 to thestorage premises 4 are closed.

The duration of adsorption and regeneration phase varies in eachindividual case.

Referring to FIG. 2, wherein like reference characters indicate likeparts as above, the adsorption apparatus has two parallel-connectedadsorption chambers 1, 1" which can either form one structural unit orcan, of course, be fitted separately from one another. During operation,adsorption proceeds in the right-hand chamber 1' and adsorbentregeneration proceeds in the lefthand chamber 1'. As shown,'the outletline from the storage premises 4 is divided into two parallel branchlines 5', 5" to connect over check valves 6, 6" to the lines 2, 2" tothe respective adsorption chambers 1, l Similar parallel connections aremade for the other main lines as shown. The direction in which theblower 3' rotates, and the direction of flow of the air in the storagepremises, during the adsorption phase is indicated by solid arrows, andthe direction in which blower 3" rotates and the direction of flow ofthe fresh air during regeneration is indicated by dotted arrows.

What is claimed is:

1. An apparatus for adsorbing carbon dioxide from air present in astorage room for perishable products comprising at least one adsorptionchamber containing a solid adsorbent therein;

a first line connected to said chamber;

a reversible blower in said line;

a first pair of lines for conveying air from the storage room throughsaid blower, said line and said adsorption chamber and back to thestorage room;

a second pair of lines for conveying a desorbent through said adsorptionchamber, said line and said blower to regenerate said solid adsorbent;and

a plurality of check valves, each check valve being disposed in arespective one of said pairs of lines for alternately opening andclosing said respective line in response to the pressure of air ordesorbent respectively therein.

2. An apparatus as set forth in claim 1 wherein said line is connectedin common to one of said first pair of lines and one of said second pairof lines.

3. An apparatus as set forth in claim 1 further comprising a pair ofsaid adsorption chambers connected in parallel, a first said lineconnected to each chamber, a blower in each said line; pairs of branchlines connected in parallel between each line of said pairs of lines andsaid first lines respectively and check valves in each said branch lineswhereby said chambers are operable in alternation with each other foradsorption and regeneration.

1. An apparatus for adsorbing carbon dioxide from air present in astorage room for perishable products comprising at least one adsorptionchamber containing a solid adsorbent therein; a first line connected tosaid chamber; a reversible blower in said line; a first pair of linesfor conveying air from the storage room through said blower, said lineand said adsorption chamber and back to the storage room; a second pairof lines for conveying a desorbent through said adsorption chamber, saidline and said blower to regenerate said solid adsorbent; and a pluralityof check valves, each check valve being disposed in a respective one ofsaid pairs of lines for alternately opening and closing said respectiveline in response to the pressure of air or desorbent respectivelytherein.
 2. An apparatus as set forth in claim 1 wherein said line isconnected in common to one of said first pair of lines and one of saidsecond pair of lines.
 3. An apparatus as set forth in claim 1 furthercomprising a pair of said adsorption chambers connected in parallel, afirst said line connected to each chamber, a blower in each said line;pairs of branch lines connected in parallel between each line of saidpairs of lines and said first lines respectively and check valves ineach said branch lines whereby said chambers are operable in alternationwith each other for adsorption and regeneration.